Stihl MS 251 Instruction Manual - Page 45

Piston Rings, that the radii face

Page 45 highlights

6.9 Piston Rings - Remove the piston, b 6.8 - Remove the piston rings from the piston. 5902RA162 TG 2310RA420 TG : Apply the installing tool 5910 890 2210 with the sleeve against the piston boss, hold the piston steady, center the tool shank exactly and press home until the snap ring slips into the groove. Make sure the tool is held square on the piston pin axis. : Use a piece of old piston ring to scrape the grooves (arrows) clean. 5902RA160 TG - Carefully fit the piston rings over the piston - they might otherwise break. : Install the piston rings so that the radii at the ring gap meet at the fixing pins in the piston grooves (arrows). : Check correct installed position of the piston rings (arrows). - Install the piston, b 6.8 - Reassemble all other parts in the reverse sequence. 2310RA421 TG 5902RA161 TG - Inspect the piston rings and replace if necessary, b 6.9 - Install the crankshaft and new oil seals, b 6.5 : Position the new piston rings so that the radii face upward (arrows). - Install the crankshaft, b 6.6 - Install the engine, b 6.5 44 MS 231, MS 231 C, MS 251, MS 251 C

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44
MS 231, MS 231 C, MS 251, MS 251 C
:
Apply the installing tool
5910 890 2210 with the sleeve
against the piston boss, hold the
piston steady, center the tool
shank exactly and press home
until the snap ring slips into the
groove.
Make sure the tool is held square on
the piston pin axis.
Inspect the piston rings and
replace if necessary,
b
6.9
Install the crankshaft and new oil
seals,
b
6.5
Install the crankshaft,
b
6.6
Install the engine,
b
6.5
2310RA420 TG
2310RA421 TG
6.9
Piston Rings
Remove the piston,
b
6.8
Remove the piston rings from the
piston.
:
Use a piece of old piston ring to
scrape the grooves (arrows)
clean.
:
Position the new piston rings so
that the radii face
upward (arrows).
5902RA160 TG
5902RA161 TG
Carefully fit the piston rings over
the piston
– they might otherwise break.
:
Install the piston rings so that the
radii at the ring gap meet at the
fixing pins in the piston
grooves (arrows).
:
Check correct installed position
of the piston rings (arrows).
Install the piston,
b
6.8
Reassemble all other parts in the
reverse sequence.
5902RA162 TG